Radio receiving arrangement



Jan. V18, 1938. H JOHANNSON 2,105,534

RADIO RECE IVING ARRANGEMENT Filed May 24, 1935 Cil 'or radiations from the radio beacon.

Patented Jan. 18, 1938 UNITED STATES iATENT OFFICE RAD-I0 RECEIVING ARRANGEMENT Application May 24, 1935, Serial No. 23,169 In Germany August 14, 1934 2 Claims.

In radio receiving arrangements for radio beacons, in the interests of effecting a saving of Weight and space, it has been proposed to use one and the same low frequency portion of the receiver for the amplification of different signals. Thus, for example, a separate high frequency amplifier and detector have been provided for receiving the actual radio beacon signals which indicate the deviation to the right or left and a l0 further high frequency receiver or detector has been provided for receiving the initial signals The low frequency circuits have however, in order to save as much weight and space as possible, been comprised in a common low frequency amplifier. The details of the high frequency and detector circuits are not of interest in connection with the invention under consideration. It may, however, be mentioned that the broad principle of the invention can be used for other purpose than the reception from radio beacons.

The receiving arrangements which have hitherto been suggested for the above-mentioned purposes, incorporate volume control methods which are in themselves known and which are based on rectifying, in the output circuit of the low frequency portion of the receiver, a part of the low frequency energy, and controlling, by means of the derived direct potential, the sensitivity of the high frequency amplifier or detector; that is to say, the high frequency portion which receives the actual radio beacon signals and the receiver which receives the initial signals are controlled in the same manner. In another suggested arrangement, the common low frequency amplier is regulated. This has the disadvantage that when approaching the initial signal emitter, or when flying over it, the sensitivity of the receiver for reception of the actual radio beacon signals is simultaneously decreased.

According to the invention amplitude or volume regulation is controlled solely by one of the signals, for example, the actual signals from the radio beacon.

The accompanying drawing shows one ernbodiment of an arrangement according to the invention. The radio beacon signals are received by the antenna A and that of the initial signals by the dipole D. It is assumed here that the radio beacon operates, for example, with a wave of approximately '7 meters and the initial signal with a Wave of, say, 3 meters. The radio beacon signals are amplified by a high frequency amplifier H and detector GI, the actual circuit details of which are not of interest here. The initial (Cl. Z-20) signals are received by the detector G2. The output circuits of GI and G2 are respectively connected to windings I and 2 of a transformer in the grid circuit of the first low frequency tube NI. Second and third low frequency stages N21- and N3 respectivelyare also provided. The third low frequency stage N3 is coupled with the second stage N2 through a lter arrangement the object of whichis to ensure that only the radio beacon signals and not the initial signal indi' cations are passed to the third low frequency stage N3. 'Ihe indications from the initial signal (or radiations) are received with the aid of lamp L through a transformer 3. The transformer is tuned by means of the condenser i and the selff induction coil 5 to the tone of the initial signal. A choke circuit 5 which is tuned to the frequency of the radio beacon is connected in series with the transformer. In practical operation, an indicator note of 1150 cycles was used for the radio beacon, and 700 or 1700 cycles was used for the initial signal. Itis of course possible when different initial signals are used, to tune the transformer circuit to the different initial signal-notes by multiple wave or to provide different transformers. The primary winding of the transformer 'l is tuned with the assistance of the self induction coil 8 and the condenser 9, to the beacon note (e. g. 1150) that is to say, it forms for this frequency a series-resonant circuit. In the secondary circuit of the transformer 'l is provided a choke circuit I0, which is tuned to the beacon frequency in order to provide a shortcircuit path for the initial signal frequency. The coupling of the third low frequency stage N3 is made through a further transformer II. The transition ratio of the transformers is chosen in known manner. The self-induction coils of the series, and choke-circuits are provided with iron cores, highly alloyed sheet metal of best quality being used as core material. The transformer II has two secondary windings one of which is connected to the grid circuit of the second low frequency stage N3, a rectifier I2 being connected through the other. The rectifier circuit as shown in the illustration is completed by resistances I3 and I4. Parallel to resistance I4 is connected a condenser I5 of sufficiently high capacity to obtain a good smoothing. The derived direct potential controls the grid potential of the detector valve Gi. As a result the rectification effect of the detector valve is varied, the recticaticn being made more or less efficient in accordance with the control voltage, that is to say the volume of sound is controlled.

It may also be thought that the regulation of the sound volume might be made in the manner customary in the wireless art. This process has, however, the disadvantage that it does not operate entirely satisfactorily on very short waves. In the case of very short waves, the capacitive influence of the high frequency valves is so great, that however great the displacement of the initial grid voltage, regulation of the sound volume only takes` place to a very limited extent, as the valves allow the high frequency to pass through capacitively and this effect cannot be eliminated, even by means of extremely high initial grid voltages. If on the other hand, the regulation is made in the detector stage of the ultra short wave receiver as above described, then the disadvantages mentioned do not occur. The capacitive transition of the high frequency through the detector tube which can of course, occur in exactly the sameway as in the high frequency tube, is of no importance as the following stages are low frequency stages, and the high frequency can therefore have no more influence on the low frequency. Y

J represents an indicator arrangement which like the receiving arrangement above described serves for the reception of beacon signals when installed on air craft for example on airplanes or ships.

In order to apply the broad idea of the invention any known method of sound volume regu lation may be used. It is immaterial if the control is effected with the aid of a resistance arrangement and additional controlling valve.

What is claimed is:

1. A radio receiving arrangement comprising a receiver of radiated signal modulated high frequency of one type, a receiver of radiated signal modulated high frequency of another type, separate detectors for the receivers, a common amplifying arrangement for the detected signals from the two receivers, frequency selecting means for separating the amplified signals into twodifferent paths, two signal indicating devices, means for delivering to one device amplified detected signals from one receiver and to the other device ampliiied detected signals from the other receiver, a rectifier, means for feeding amplified detected signal energy from one receiver to said rectifier, and means for utilizing the direct current so derived by said rectifier to control the amplitude of the signal modulated high frequency in one of said receivers.

2. A radio receiving arrangement comprising an ultra short wave receiver for receiving radio beacon signals, an ultra short wave receiver for receiving an initial signal, separate detectors for the receivers, a common amplifying arrangement for the detected signals from the two receivers, means for separating the amplified signals, two

signal indicating devices, means for delivering to f one of said devices amplified detected signals from one of said receivers and to the other of. said devices, amplified detected signals from the other of said receivers, a rectifier, means for feeding energy of the detected radio beacon signal to said rectifier and means for utilizing the direct current so derived by such rectifier to control the amplitude of the signal impressed upon the detector of the radio beacon signal receiver.

HELMUT JOHANNSON. 

